[Determination of substrate specificity of fucosyltransferase from rat brain using synthetic acceptors].

The substrate specificity of fucosyltransferase (FT) from rat forebrain and cerebellum was studied using synthetic acceptors. Of 16 acceptors tested, only those containing the Gal beta 1-4GlcNAc beta 1-R fragment were subjected to enzymic fucosylation. The isomer with a 1-3 bond as well as lactose and oligosaccharides with an additional Neu5Ac residue attached to Gal or a Fuc residue attached to GlcNAc were not fucosylated whereas Fuc alpha 1-2Gal beta 1-4GlcNAc displayed the same substrate properties as Gal beta 1-4GlcNAc.

[The effect of glycolipids [correction of glycoproteins] on the oligomeric structure and catalytic activity of alpha-L-fucosidase from human kidneys].

alpha-L-Fucosidase (EC 3.2.1.

[Human glycosidase in the AOT reversed micelle system: features of properties and kinetic regularities of catalysis].

Kinetic of hydrolysis, by lysosomal glycosidases, of their synthetic substrates were studied in systems of the Aerosol OT (AOT) reversed micelles in octane. Catalytic activity of all the tested enzymes, viz., GM1-galactosidase, beta-hexosaminidases A and B, neuraminidase, and galactocerebrosidase, in reversed micelles proved to be the same as or higher than in the water buffer.

[Changes in the organization of the intermediate filament system of human fibroblasts in lysosomal storage diseases and their modeling].

The organization of the system of the vimentin intermediate filaments (IFs) in human fibroblasts in lysosomal storage diseases (Fabry's disease, mannosidosis) and their modelling has been studied in vitro. It was shown that during accumulation of nonhydrolyzable compounds, hypertrophy of the lysosomal compartment is accompanied by formation of ring-shaped bundles IFs, surrounding apparently these increased organelles. The changed organization of IFs is characteristic of polarised pathological cells in monolayer, and after repassage it is retained only at the spreading state; on transition from the discoid to extended cellular form there occurred the centrifugal shift of ring-shaped structures of IFs to active cell border and gradual restoration of radial fibrillar state of IFs.

[Intravital determination of pH gradient between the cytoplasm and lysosomes in human fibroblasts in the normal state and in hereditary storage diseases].

Presented are the results of measurements of pH in cytoplasm and lysosomes of skin fibroblasts of healthy donors and patients with lysosomal storage diseases, mannosidosis, Fabry, Krabbe disease. The pH value was estimated in the stationary phase of growth using neutral red (lysosomes) and fluorescein diacetate (cytoplasm). It was shown that the cytoplasmic pH value in pathological cells didn't virtually differ from the control values.

[Regulation of supermolecular organization and catalytic activity of the lysosomal complex GM1-galactosidase and neuraminidase in vitro].

The regulation of the catalytic activity and supramolecular organization of human kidney Gm1-galactosidase and neuraminidase was investigated in the reversed micellar systems of Aerosol OT in octane. It was found that in the reversed micellar systems the Gm1-galactosidase can exist in the monomeric, tetrameric or octameric forms depending on the H2O/surfactant ratio in the system which determines the micelle size. The association of Gm1-galactosidase monomers into octameric structure characteristic of Gm1-galactosidase in the lysosomes results in a two fold increase of the specific catalytic activity of the enzyme.

[A pH increase in human fibroblast lysosomes during accumulation of non-hydrolysable compounds].

The changes in intralysosomal pH were measured in the stationary phase of normal human embryonic fibroblast growth under sucrose loading over a period of 6 to 120 hours and in cells with a typical lysosomal storage pathology, Fabry's disease, using a vital indicator dye, neutral red. It was shown that long-term hypertrophy of the lysosomal compartment during intracellular accumulation of non-hydrolysable compounds is concomitant with a pH increase, on the average, by 0.4 units.

[Substrate specificity of multiple forms of human alpha-D-galactosidase and alpha-D-fucosidase].

It was shown that human alpha-D-galactosidase is represented by multiple forms, only one of which can also split alpha-D-fucoside. Fabry's disease was found to be associated not only with the deficiency of the alpha-D-galactosidase total activity but also with the deficiency of the alpha-D-fucosidase activity. The decrease in the alpha-D-galactosidase activity is due to the lack of two enzyme forms, while the profile of alpha-D-fucosidase multiple forms during isoelectric focusing of human enzyme preparations is modified very little in comparison with the normal one.

[Change in intracellular activity and secretion of various lysosomal glycosidases of human fibroblasts cultured in medium with sucrose].

Intracellular activation of lysosomal glycosidases from human skin fibroblasts (alpha-L-fucosidase, beta-D-hexosaminidase, beta-D-galactosidase and beta-D-glucuronidase) was shown to occur on the 3rd-6th days of cultivation in media containing 0.04 M sucrose. The increase in the enzyme activity ranged from 40 to 300% depending on cell strain, nature of enzyme and cultivation time.

[Isolation and identification of products of accumulation in Fabry disease].

Three fractions of glycolipids--monohexosylceramide, dihexosylceramide (DHC) and trihexosylceramide (THC) were isolated from kidney of patient with Fabry disease. As compared with normal state amount of DHC and THC was increased in the patient kidney 9-19-fold and 15-26-fold, respectively. Gas liquid chromatography showed that the DHC fraction consisted in digalactosylceramide, while the THC fraction--a mixture of digalactosylglucosylceramide (90%) and trigalactosylceramide (10%).

[A study of various properties of beta-galactocerebrosidase from human chorion using synthetic fluorescent substrates].

The properties of beta-galactocerebrosidase from human chorionic villi, cultured chorionic villi and cultured skin fibroblasts were compared, using 6-hexadecanoylamino-4-methylumbelliferyl-beta-D-galactopyranoside (HMGaL) as substrate. The effects of bile salt and Triton X-100 on beta-galactocerebrosidase were examined. It was shown that optimization of the HMGaL assay system requires the presence of pure sodium taurocholate and Triton X-100 at concentrations of 4.

[Study of the specificity of human lysosomal glycolipid hydrolases using synthetic fluorogenic substrates].

On the basis of o-acylamino-4-methylumbelliferon, a number of beta-galactosides and beta-glucosides have been synthesized. The fluorogenic compounds obtained differ by the length of acyl residues. 6- and 8-hexadecanoylamino-4-methylumbelliferyl-beta-D-galactopyranosides (6-HMGal and 8-HMGal) are shown to be substrates for human galactocerebroside-beta-D-galactosidase.

[Identification of Krabbe disease in 2 brothers from East Germany using a new fluorogenic substrate for galactocerebrosidase].

Activity of several lysosomal hydrolases was studied in skin fibroblasts obtained from two brothers living in GDR. Both patients exhibited distinct clinical symptoms of severe neurovisceral disease. Analysis of the lysosomal enzymes activity enabled to exclude possible occurrence in the patients of such glycolipidoses as Gaucher's disease, Sandhoff's disease, GM1-gangliosidosis and metachromatic leukodystrophy.

[Characteristics of biogenesis and substrate specificity of lysosomal glycosidases under normal conditions and in glycosidoses].

Main steps are considered of posttranslational modification of lysosomal hydrolases, which are glycoproteins. Processing of the enzymatic carbohydrate moiety in various compartments of endoplasmic reticulum and Golgi apparatus is discussed. Importance of mannose-6-phosphate groups formed during the processing is revealed by studies on binding of these enzymes with specific receptor responsible for their transport into lysosomes.

[Biochemical diagnosis of Anderson-Fabry disease in two brothers].

Activity of several lysosomal enzymes was studied in leukocytes, blood plasma and skin fibroblasts of two adult brothers with clinical diagnosis of Fabry disease. Activity of ceramide trihexoside-galactosidase was distinctly decreased in both patients. The residual enzymatic activity constituted 5-6% in the patients leukocytes, less than 10% in blood plasma and 25% in fibroblasts as compared with controls.

[Secretion of alpha-L-fucosidase by human embryonal skin fibroblasts].

The amount of alpha-L-fucosidase secreted by normal human fibroblasts was higher in the medium containing 10% bovine serum than in the medium containing 0.1% bovine serum. Glycosidase secretion was twice higher at the advanced than at the initial stage of subcultivation.

[Intracellular activity and secretion of various lysosomal glycosidases in cultured human skin fibroblasts].

The intracellular activities of four lysosomal glycosidases (alpha-L-fucosidase, beta-D-hexosaminidase, beta-D-galactosidase and beta-D-glucuronidase) in human skin fibroblasts cultured in a medium with 0.1% serum increased in a greater degree than that in a medium with 10% serum. Only two glycosidases (alpha-L-fucosidase and beta-D-hexosaminidase) were secreted by fibroblasts in the culture medium.

[A new fluorogenic substrate for human galactocerebroside-beta-D-galactosidase].

A new fluorogenic compound--6-hexadecanoylamino-4-methyl-umbelliferyl-beta-D-gala cto pyranoside (HMGal), a substrate for human galactocerebroside beta-D-galactosidase (HG), has been synthesized. A method for determining the HG activity based on the use of HMGal as a fluorogenic substrate has been developed. The specificity of HMGal hydrolysis by HG has been demonstrated in experiments with enzyme preparations from human skin fibroblasts and leukocytes in normally and in hereditary glycolipidosis (GM1-gangliosidosis and Krabbe's disease).

[Separate factors influencing the interaction of carbohydrate- containing liposomes with galactose-specific lectins].

Some natural (Gal-Cer, Lac-Cer, desyalylated gangliosides) and synthetic (HMGal) glycolipids differing in the length of the bridge linking the terminal galactose with the hydrophobic moiety were incorporated into the liposome membranes. The precipitation of the thus obtained vesicles induced by galactose-specific lectin RCA was studied. It was shown that when the amount of the glycolipids used for the incorporation into the liposomes (1 mol.

[Lysosomal glycosidase activity in cultured human fibroblasts].

A study was made of the activity of 3 lysosomal glycosidases -beta-D-galactosidase (K. P. 3.

[Use of fluorescence-labelled cerebroside as a substrate for galactosylceramidase of human skin fibroblasts].

Possible use of the fluorescently labelled cerebroside, 1-O-(beta-D-galactosyl)-2-N-[6-(2-antroyl)hexanoyl]-4-sphingeni n (Gal-A-sphingenin) as a substrate for galactosylceramidase (GC) from human skin fibroblasts was investigated. Studies involving TLC and fluorimetric methods revealed enzymatic splitting of Gal-A-sphingenin whose degree correlated with the amount of the enzyme and incubation time. Some kinetic parameters of GC were determined, using Gal-A-sphingenin as substrate.

[Total activity and distribution of multiple forms of lysosomal glycosidases in subfractions of human leukocytes].

Activities of N-acetyl-beta-D-hexosaminidase, beta-D-galactosidase, alpha-D-mannosidase and alpha-L-fucosidase were studied in granulocytes and agranulocytes of human blood. Hexosaminidase exhibited the highest activity in the both leukocyte fractions. At the same time, activities of hexosaminidase and galactosidase were higher in a granulocytes.